1. Field of the Invention
The invention relates to a heart valve prosthesis consisting of a support ring with at least two, preferably three, commissure supports and flexible (or semilunar) cusps, and to preferred processes for producing them. Such prostheses are used for the replacement of aortic valves or pulmonary valves on human hearts.
2. Background Information
In recent years, a number of cusp valve prostheses have already been disclosed, wherein attempts were made by means to the most diverse design forms to imitate the natural aortic valve or pulmonary valve as closely as possible with respect to function and structure. For example, German Patent Specification No. 2,355,959 describes a semilunar valve for replacing the aortic valve or pulmonary valve, which has the essential structural feature that it is so flexible in its cross-section that it is able to follow the changes in size and cross-section of the base of the aortic valve or pulmonary valve. Although such a highly flexible system has certain advantages, it has the technical functional disadvantage that, in the event of excessive stretching, the cusps can flap over. Moreover, it is difficult to fix the textile suture ring, by means of which the prosthesis is fastened to the heart, to a support ring of such flexibility.
A very important disadvantage of this and other known heart valves is, however, above all that the height of the commissure support is equal to the height of the cusp valves, so that the forces arising during the opening and closing movement of the cusps are applied particularly to the tips of the commissure supports and can cause cracking at these stressed points.